1. Field of the Invention
This invention relates to an image processing apparatus and, more particularly, to an image processing apparatus for processing a dot-pattern image typically represented by a font, by way of example.
2. Description of the Related Art
Ordinarily, an image pattern typified by a font used in an electronic image output device such as a printer or CRT is composed of dots. When such a dot pattern is outputted by these output devices, the contour of the outputted image pattern develops a step portion. These step portions produce a visible roughening of the image and become more pronounced the lower the resolution of the device. In particular, when a dot pattern is formed in a case where an incline exists near the auxiliary scanning direction (hereinafter referred to as the "vertical direction") or in the main scanning direction (hereinafter referred to as the "horizontal scanning direction"), as shown in FIG. 1A, step portions are produced, as shown in FIG. 1B. Specifically, the image exhibits pronounced roughening, as represented by the step portions indicated by the arrows P1 through P4.
Despite the fact that the image pattern outputted by the aforementioned image output devices is required to have a much higher quality, the visible roughening of the image is one significant factor that invites a deterioration in the quality of the output image pattern. One method of preventing visible roughening is to provide an image pattern based on a Gray-font scale composed of pixels having different brightness over several step portions, as well as a generating device especially for this pattern. The only result has been to express visible intermediate brightness which corrects for roughness or to raise the resolution possessed by the device.
However, with the example of prior art described above, not only is the construction of the apparatus complicated but costs are higher regardless of the method used.